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28 Cards in this Set
- Front
- Back
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growth of microbes after it has gained access to host tissues
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Colonization
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When does colonization begin?
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During the birthing process
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an organism that harbors a parasite
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Host
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an organism that lives on or in the host and causes damage
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Parasite
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the ability of a parasite to inflict damage
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Pathogenicity:
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causes disease only when host defense is lowered
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Opportunistic pathogen
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the quantitative measure of pathogenicity
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Virulence
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urogenital, respiratory, and digestive tracts.
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Where the bacterial infections usually occur
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omething that promotes tooth decay (such as sugar or certain bacteria)
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Cariogenic
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organic acids that cause tooth enamel to become decalcified.
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Streptococcus mutans
Streptococcus sobrinus |
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Functions & products of GI flora
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Vitamins B12 and K are made by bacteria!
Steroid compounds are modified by bacteria! |
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Upper Respiratory Tract
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Resident microflora include staphylococci, streptococci, diptheroid bacilli, gram-negative cocci.
Pathogenic S. aureus and S. pneumoniae can be found in people who are carriers. |
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Lower Respiratory Tract
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Lower RT has no resident microflora in healthy adults!
Pathogens can reach the lower RT and cause disease. |
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Urogenital tract
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Microbes commonly found:
L. acidophilus Streptococci E. coli Various yeasts |
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Means of attachment: fimbriae & pili
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Fimbriae: shorter and more numerous
Pili: longer and fewer |
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Once inside the body, what’s important for colonization and growth?
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Temperature
pH [O2] Nutrients! Sugars, amino acids, organic acids, minerals, trace elements, etc. |
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LD50
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the dose of a pathogen needed to kill 50% of animal test subjects
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Attenuation
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a decrease or loss of virulence
Often done on purpose to create viral vaccines |
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Toxicity
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the ability of an organism to cause disease by means of a toxin that inhibits or kills host cells
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Invasiveness
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the ability of a pathogen to grow in host tissue in such large numbers that it inhibits host function.
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Virulence factors
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In addition to capsules, slime layers, fimbriae, and pili…
Hyaluronidase (breaks down ‘intercellular cement’) Proteases Nucleases Lipases Collagenase Etc. |
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Fibrin functions in blood clotting.
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Some microbes degrade fibrin, so they can spread from site of infection
Some microbes promote fibrin formation to protect themselves. |
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toxic proteins released from pathogen, travel to distant sites and cause damage
Three categories: 1. cytolytic toxins 2. AB toxins 3. Superantigen toxins (will discuss later) |
Exotoxins
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Hemolysis: destruction of blood cells
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Cytolytic (exo) toxins
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Consist of 2 subunits, A and B.
B binds to receptor on cell surface, allowing transfer of A into cell, causing damage. |
AB(exo) Toxins
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exotoxins that affect the small intestine
Usually results in vomiting and diarrhea Usually from eating contaminated food |
Enterotoxin
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toxic lipopolysaccharides embedded in cell wall of gram-negative microbes
Lipid A is the part that’s toxic! Cause fever, diarrhea, loss of white blood cells and platelets, etc. Large doses can cause death, but they are much less toxic than exotoxins. |
Endotoxins
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Innate Resistance
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Natural host resistance-different species have different susceptibilities to infection
Tissue specificity Ex: enteric bacteria won’t cause a wound infection, while wound-infecting bacteria won’t cause GI distress Physical and chemical barriers Skin, cilia, acidity, normal microflora, lysozyme, etc. |
